Band lap



Feb. 6, 1945. R. B. MENTZER BAND LAP Filed Feb. 25, 1943 FIG. 2.

4 FIG. 3.

FIG.

FIG. 4.

FIG. 5.

INVENTOR. RALPH B.MENT ZER HIM-Il Patented Feb. 6, 1945 UNITED STATES PATENT OFFICE Ralph Bender Men t zti j l lllzollaniPa assignor to Hamilton Watch Company, Lancaster,

Application February 25, 1943, Serial No. 477,094

This invention is directed to an apparatus for sawing hard material such as used to make watch jewels. The procedure employed in the cutting "or jewels or jewelmaterial is tedious and wasteful. The material, which is usually synthetic sapphire is extremely hard; in fact it can only be efficiently cut with diamonds, and takes considerable time to make the lightest cut. The material generally used to saw these jewels is diamond dust embedded in soft copper. The problem'is to avoid waste by reason of wide cuts and g to make the saw sufliciently strong to stand continual use. I

The present invention is directed to a saw which will accomplish these ends and will be economical and practical to use; a

It is the object of the present invention to provide a cutting means for hard material that will make repeated accurate narrow cuts. I f

It is a further object to provide a saw for jewel material that will not wastethe material by wide cuts.

It is a further object to provide a saw of the band saw type that will exert even pressure against the material to be cut. It is a still further object to provide a fine soft copper blade so held in the apparatus that it will make repeated accurate narrow cuts. It is a still further object to provide an app?- ratus that is semi-automatic in operation, requiring only periodic control by the operator. It is a further object to provide an apparatus of the band saw type, using a narrow diamond dust charged copper blade in which the blade is urged continuously into the material to be cut.

It is a still further object of the invention to provide means for adjusting the blade urging means to provide for difierent thicknesses of saw blades and different depths of cut. f

It is a further object to provide a combination of means for guiding the saw blade with means for urging it into the work. I,

It is a still further object to provide a pair of cones serving both as a guide and as a mean 3 Claims. (01. 125-21) Fig. 3 is a broken plan of the copper strip used as a saw and showing the diamond dust exaggerated.

Fig. 4 is a section on line 4-4 of Fig. 3.

Fig. 5 is a detail view of the apparatus showing theblade guiding and urging means.

, Fig. 6 is a perspective of the strips of'jewel material mounted on a block and showing three cuts made by this apparatus.

The apparatus is of the customary band saw construction generally with a base I supporting a standard 2. A supporting plate 3 secured both to the base I and standard 2 carries a lower wheel 4 having a flange on whose outer surface a copper strip 6, in the form of a band saw blade travels. The wheel 4 is journaled at I and is driven through drive wheel 8, belt 9, motor pulfrom the workpiece.

ley I ii and motor II which is connected to a source of current at l2.

Carried on the standard 2 is a frame work I3 which supports parallel rods H and I5. Slidably mounted on these rod is a hearing it which carries a top wheel ll adjustable in a vertical direction through the screw 18. A casing l9 encloses this part of the apparatus all of which is conventional band saw construction.

A work table 29 is supported on brackets 2| attached to the supporting plate 3. Securely lastened to said work table is a gibbed slide 22 for moving the workpiece into engagement with bolts or the like is an L-shaped support 29 which is positioned on the side of the lap blade away support are two frusto-con'ical. guiding rollers 30 and 3| and a cylindrical roller 32.. It is necessary to hold the copper cutting strip which will hereafter be referred to asthe lap in a perfectly straight line at; least for the length of the cut.

These cuts are only .010 thick and are spaced generally .030. l

" To maintain a perfectly straight line two frusto-conical guide rollers are used above the workpiece with a single cylindrical roller below said workpiece. The line of travel of the saw is moved beyond a common tangent to the two wheels, mainly to cause the lower cylindrical Carried on this L-shaped roller 31 and cylindrical roller 32.

I block of v-transite or similar material.

sticks are held to :the block and to each other The saw blade 6 is formed of thin strip solitcopper, phosphor bronze or the like and has dia- 'mond dust 35 rolled into its cutting edge; "Qnef application is generally enough to make approxi-- The method of affixing this dust mately 60 cuts. is to apply a paste of diamond. dust andgoil to the edge of the strip and rolling it into the copper with a hard roller.

:The material whichthe lap is used upon is the long sticks 36'whichhave been outirom' the boule and which are mounted in parallel relation on a These by sealing wax- 3! or some othersubstance such 'as stick shellac or the like. The apparatus cuts across the face of the; parallel sticks along line 38 asshoWninFig.6. i

The operation is as follows:

.' -The workpiece 25- is'secured. on slide 23 and by manipulation of slides Hand 23 is brought 'intoposition for thefirst cut. I p

I l A stream of water 39 from pipe 40 is directed against the band lap-adjacent the workpiece. I Both of the threaded adjustments 2! and 28' are so calibrated that exactly one turn will producei'thedesired out. The lapping band is, of

course, turning and the block is brought just into engagement with the cutting edge, the block being positioned for the first out Now a full turn-"oi" the screw 21 forces the sticks againstthe band andiorces the band-back between the frustoconical rollers whose tendency is to urge said band outward. This tendency causes the --band i-to.,., bear against the -sticks with an even balanced" pressure tending to cut inan exact straight-line --until the cut is finished -Further movement of theslides places the workpiece in position to re- ;peat the operation.

The precise nature of the work can only be realized by comparing figures. Formerly with a wide saw cut, that is using the thinnest saw which would give parallel cuts, the cuts were .015 of an inch thick. Using the present saw, cuts running about .005 of an inch are made, thus creating a saving of vital material as well as the increase in time necessary to make changes in machine.

This is accomplished by the guiding means that 'forces the saw into the jewel material at an even rate and without tendency to waver or deviate '3 from a straight line.

:Whatis claimed is: v

1. An apparatus for cutting jewel material :comprising ajmoving band lap element, a pair of irusto-conical shaped *resilient rollers embracing said band elements on opposite sides, a'workhold- ,er;; s-upporting-a workpiece, means for moving saidworkpiece against bandlap element to force said" band lap toward the base end of said frustoconical rollers the inherent actionrofi.said rollers serving to force the-band lap against the workpiece sufficiently to complete the cut; m

2 -An apparatus :for :cutting jewel material comprising a verticallymovable band lap element, a pair of resilient 'frusto-conical shaped rollers embracing said element on oppositesides and in the same plane, a workholder supporting a workpiece, means foriorcing said workpiece against said band lap element to move said band lapelement toward the base ends of said frustoconical rollers the resilient andinherent action of said irusto-conioal rollers serving'to force said band lap against said workpiece sufficiently to complete the cut. r p

3;;An apparatus for cutting vjewel material comprising a moving'bandelement, a pair ;of-resilient frusto-conical rollers mounted on parallel axes embracing saidband-lap element on opposite sides and in thesame plane, aworkholder supporting a workpiece,-means for. forcing said workpiece against band band lap to move said band lap toward the frusto-conical rollers and toward 1.theirv bases, the inherent resilient action 0f said -rollers servingto force the band lap element against said workpiece sufiiciently to complete the cut. 7 1 i 3 RALPHKMENTZER- 

